This invention relates to actuators used in aircraft door lock mechanisms. More specifically, this invention relates to systems and methods for improving the reliability of aircraft door flight lock actuators. Flight lock actuators are used in aircraft door lock mechanisms to secure a lock mechanism in the locked position during flight, or whenever aircraft power is supplied to the actuator. During flight, for safety reasons, it is conventional practice to maintain the flight lock actuator in a powered stall against its locked position stop. When aircraft power is removed at the end of the flight, the flight lock actuator is conventionally returned to its unlocked position by a spring system. For safety reasons, limit switches and brakes are not permitted in flight lock actuators.
Actuators built according to the present art suffer occasional failure due to damage from abruptly impacting mechanical stops at the end of an actuator's stroke, especially while being back-driven by a spring system during the unpowered extension stroke to the unlocked position. These repeated mechanical shocks to the internal mechanism of a flight lock actuator can cause jamming and mechanical failure of the actuator. In addition, actuator failure may also result from damage to a brush-type actuator motor due to prolonged periods of powered stall in the locked position. The aircraft flight lock actuator is a key safety element in an aircraft. Any failure in the door lock mechanism, including the flight lock actuator, should be avoided.
Therefore, it would be desirable to provide a redundant stored energy system to power the flight lock actuator's extension stroke to the unlocked position stop. It would be further desirable to extend and retract the flight lock actuator to its mechanical stops in a controlled manner, so as to eliminate failure due to damage from abrupt impacts. It would be further desirable to power the flight lock actuator using a motor less prone to suffer damage from prolonged periods of powered stall.
In view of the foregoing, it is an object of this invention to provide a flight lock actuator using systems and methods that significantly improve its reliability.